Caffeine and attentional control: improved and impaired performance in healthy older adults and Parkinson’s disease according to task demands

Introduction Caffeine is frequently consumed to boost goal-directed attention. These procognitive effects may occur due to the adenosine-mediated enhancement of monoamines, such as dopamine, after caffeine administration. As such, caffeine’s beneficial effects may be altered in conditions such as Parkinson’s disease (PD). However, whether caffeine improves cognition, and at what cost, has not been experimentally established in patients with neurodegenerative disease. Methods Single-dose trials to probe cognitive effects of caffeine are often confounded by short-term caffeine abstinence which conflates caffeine’s effects with treatment of withdrawal. Using a placebo controlled, blinded, randomised trial design, we assessed the effect of 100 mg of caffeine across well-established tasks (Choice reaction time, Stroop Task and Rapid Serial Visual Presentation Task; RSVP) that probe different aspects of attention in PD patients (n = 24) and controls (n = 44). Critically, participants withdrew from caffeine for a week prior to testing to eliminate the possibility that withdrawal reversal explained any cognitive benefit. Results Caffeine administration was found to reduce the overall number of errors in patients and controls on the Stroop (p = .018, η2p = .086) and Choice reaction time (p < . 0001, η2p = .588) tasks, but there was no specific effect of caffeine on ignoring irrelevant information in the Stroop task. On the RSVP task, caffeine improved dual item accuracy (p = .037) but impaired single item accuracy (p = .044). Across all tasks, there was little evidence that caffeine has different effects in PD participants and controls. Conclusion When removing withdrawal effects as a factor, we demonstrate caffeine has beneficial effects on selective attention but is a double-edge sword for visual temporal attention and would need careful targeting to be clinically useful.

The Cognitive Consequences of the COVID-19 Pandemic on Members of the General Population in Italy: A Preliminary Study on Executive Inhibition

The pandemic period which has characterized the last two years has been associated with increasingly worsening psychological conditions, and previous studies have reported severe levels of anxiety, mood disorder, and psychopathological alteration in the general population. In particular, worldwide populations have appeared to present post-traumatic stress symptoms (PTSS). Surprisingly, no studies have evaluated the effect of COVID-related PTSS on cognitive functioning. This study focused on the association between high levels of PTSS related to COVID-19 and alterations in executive functioning by considering executive inhibitions in populations not infected by the virus. Ninety respondents from the Italian population participated in the study. A higher percentage of PTSS was reported. Moreover, respondents with high post-traumatic symptomatology presented deficits in the inhibition of preponderant responses, demonstrating an executive deficit which could be expressed by a difficulty in controlling goal-directed actions. This was underlined by worse performances in elaborating incongruent stimuli in the Stroop task and no-go stimuli in the Go/No-Go task. This report presents preliminary findings underlining the effect of the COVID-19 pandemic on cognitive functions. The results confirmed a persistently higher post-traumatic symptomatology related to the COVID-19 pandemic in the Italian population and highlighted an association with cognitive inhibition impairment.

Is There Semantic Conflict in the Stroop Task?

This research addressed current controversies concerning the contribution of semantic conflict to the Stroop interference effect and its reduction by a single-letter coloring and cueing procedure. On the first issue, it provides, for the first time, unambiguous evidence for a contribution of semantic conflict to the (overall) Stroop interference effect. The reported data remained inconclusive on the second issue, despite being collected in a considerable sample and analyzed with both classical (frequentist) and Bayesian inferential approaches. Given that in all past Stroop studies, semantic conflict was possibly confounded with either response conflict (e.g., when semantic-associative items [ SKYblue] are used to induce semantic conflict) or with facilitation (when color-congruent items [ BLUEblue] are used as baseline to derive a magnitude for semantic conflict), its genuine contribution to the Stroop interference effect is the most critical result reported in the present study. Indeed, it leaves no doubt – in complete contrast to dominant single-stage response competition models (e.g., Roelofs, 2003 ) – that selection occurs at the semantic level in the Stroop task. The immediate implications for the composite (as opposed to unitary) nature of the Stroop interference effect and other still unresolved issues in the Stroop literature are outlined further.

Head-Down Tilt Bed Rest Improves Executive Function Amongst Younger Adults: A Pilot Project

Purpose Microgravity has been shown to be a significant stressor on the cardiovascular system and the brain due to the redistribution of fluids that occurs in the absence of gravitational force, but there is scarce literature surrounding the effects of microgravity on cerebral hemodynamics and cognition. Understanding the early effects that simulated gravity has on cognitive function is essential for developing proper physical and cognitive countermeasures to assure safe and effective cognitive/decisions making while astronauts prepare for the initial launch or when they arrive in a microgravity environment. Therefore, this study aims to determine how an acute simulation of microgravity would alter cerebral oxygenation and executive functions. Methods Sixty-five young healthy participants (22±6 years, 21 females) completed a thirty (30) minute horizontal (00 tilt) followed by a 90-min -6° head-down-tilt (HDT) protocol. Cerebral oxygenation in the prefrontal cortex was monitored throughout the testing session using near-infrared spectroscopy. Cognition was also measured using a computerized Stroop Task. Results Our results demonstrate that cerebral oxygenation was higher during HDT compared to the horizontal supine position (9.11±1.3 vs 7.51±1.8, p=0.02). For the cognitive results, the non-executive performance of the Stroop task remained stable during HDT (652.46± 19.3 vs. 632.49±14.5, p=0.09). However, reaction time during the executive task performance was improved after the HDT (1058±195 msec to 950±158 msec, p<0.01). Conclusion Our results suggest that an acute bout of simulated microgravity can enhance executive functioning.

Creativity in the Predominantly Inattentive and Combined Presentations of ADHD in Adults

Objective: ADHD and its associated inhibition deficits might promote creativity. However, results in the literature are conflicting, possibly due to the heterogeneity of ADHD. To control for this heterogeneity, creativity, and inhibition were investigated in the predominantly inattentive (ADHD-I) and combined (ADHD-C) presentations. Method: Participants were males/females aged 18 to 51, diagnosed with ADHD-I ( n = 21), ADHD-C ( n = 19), or without ADHD ( n = 43). Self-rated Kaufman Domains of Creativity Scale and evaluator-rated figural Torrance Test of Creative Thinking (TTCT) were used for measuring creativity, Stroop task for inhibition, and Conners’ Adult ADHD Rating Scales for ADHD symptoms. Results: The ADHD-C group reported higher self-rated creativity than other groups and made more original drawings paired to more abstract titles in the figural TTCT than controls. Conclusion: ADHD-C participants were the most creative. This result was more importantly associated with higher degrees of ADHD symptoms rather than poorer inhibition.